The subject matter disclosed herein relates to power limiting for a programmable input/output (I/O) device, and more particularly, to systems and methods for monitoring and limiting current in a digital-to-analog converter (DAC) and application specific integrated circuit (ASIC) I/O device.
Control systems, such as programmable logic controllers (PLCs) and distributed control systems (DCSs) often include a programmable input/output (I/O) device which includes an application specific integrated circuit (ASIC) for switching signals between user terminals and a digital-to-analog converter (DAC) with both current and voltage outputs. When the DAC is in a voltage output mode, the DAC maintains a constant voltage output to a load. The constant voltage output of the DAC behaves as a voltage source, varying the output current in relation to the load impedance in order to keep the output voltage constant. In the case that the load is shorted, a large amount of current may flow from the DAC, potentially damaging and/or overheating the DAC as well as the ASIC. Additionally, certain load types may draw a large amount of power through the programmable I/O device, also leading to damage of the device, or a device that contains the programmable I/O device.